Photocatalytic decomposition of textile dyestuffs by photosensitive metal oxide catalysts

Textile azo dyes are one of the pollutants in waste water that adversely affect human and environmental health. Removal of these chemicals from wastewater is important for eco-system and human health. In this study, Bi₂O₃ nanoflakes and ZnO were synthesized by the co-precipitation method. Adsorption and photocatalytic degradation reactions were carried out to remove dyes (Victoria blue (VB) and Malachite green (MG)) from wastewater with the photocatalysts. In order to improve the activity of catalysts, cetyltrimethylammoniumbromide (CTAB) was added as a surfactant to pure oxide structures, and Bi₂O₃-CTAB and ZnO-CTAB catalysts were prepared. The structural and morphological properties of these catalysts were determined by BET, XRD, DRS, FTIR, and SEM analysis. It was found that the activity of the catalyst was improved by adding surfactant to the Bi₂O₃. The total mineralization of VB dye was completed in 60 min under sunlight with Bi₂O₃-CTAB catalyst. However, the degradation of the MG dye with the same catalyst under UV-C irradiation could be completed in 120 min.